Private systems for delivering audiovisual programming to authorized subscribers are popular and widely used throughout the world. Cable television is a prime example of such a system. Additionally, a private system for delivering audiovisual programming to authorized subscribers may be a pay-per-view system in a residence or in a public establishment such as a hotel, or a communication system used by an organization, private or governmental, to provide audiovisual programming to members of the organization.
The basic premise of private systems for delivering audiovisual programming to authorized subscribers is that only authorized subscribers should be able to receive the programming. In the interests of security, privacy or to enable the provider to charge a fee for the programming, those who are not authorized subscribers must be prevented from receiving the programming.
The traditional, straightforward method of excluding unauthorized parties from accessing the transmitted audiovisual programming is for the programming provider to scramble or encode the signal carrying the programming prior to transmission. Authorized subscribers who have paid for the programming or who are cleared to receive the programming are provided with a descrambler or decoder unit which unscrambles or decodes a signal carrying the programming.
After the signal is unscrambled or decoded the programming can be properly perceived by the authorized subscriber. This decoder unit is referred to as a set top box, the set being the monitor, tuner or other device with which the transmitted programming is received. Unauthorized parties who do not have the set top box with be unable to receive the audiovisual programming in an intelligible form.
As used herein, "audiovisual programming" or "audiovisual signal" includes video and audio signals, whether transmitted alone or in combination as well as data, games (or other programs), graphics, control, telephony, text or other information independent of format. This programming may be transmitted from the programming provider to the authorized subscribers by wire or broadcast within the meaning of the present invention. As used herein, "set top box" is intended to broadly include satellite receivers, LMDS or MMDS or any IRD (integrated receiver/decoder).
A typical design for a set top box is illustrated in FIG. 1. As shown in FIG. 1, a conventional set top box 100 receives an input audiovisual signal through an input terminal 102. The signal received at input terminal 102 is provided to a standard function circuit 101.
The standard function circuit 101 contains the necessary circuitry, decryption keys, etc. to decode the audiovisual signal received through input terminal 102. Alternatively, the function circuit 101 may enhance the audiovisual signal. The standard function circuit 101 converts the input signal to a form in which it can be intelligently perceived when supplied to a monitor, tuner, television or other receiver device. The decoded signal is output by the standard function circuit 101 to an output terminal 103. The receiver device (not shown) is then connected to the output terminal 103.
The set top box 100 also includes a power controller 104 which receives power from a power input terminal 105. The power controller 104 provides power from the power input terminal 105 to the standard function circuit 101. In this manner, the set top box 100 allows the authorized subscriber who possess it to receive and use the transmitted audiovisual signal.
However, the set top box 100 and standard function circuit 101 may readily become obsolete for a variety of reasons. For example, in the interests of security, the method of encoding and decoding the audiovisual signal may be periodically changed by the signal provider. Similarly, the signal provider may simply upgrade the encoding system periodically to incorporate new features and functions. The service provider may also offer additional channels of audiovisual signals which are encoded using new or different methods. If the function circuit is enhancing the audiovisual signal, better methods of performing the enhancement may become available.
Additionally, the standard function circuit 101 may simply malfunction or become damaged. In any of these instances, the standard function circuit 101 will no longer allow the authorized subscriber to completely or optimally receive the audiovisual signals transmitted by the provider.
The solution to this problem in the past has been to provide authorized subscribers with a new set top box containing an updated standard function circuit. The updated function circuit is designed to fully receive and translate the signals transmitted by the signal provider.
However, this solution is obviously expensive and time consuming, especially if authorized subscribers are widely spread over a large geographic region. Thus, there is a need in the art for a method and apparatus of readily and inexpensively upgrading set top boxes in the field.